Thermolysis of 7-(Acylamino)-7-azabenzonorbornadienes and 1-(Acylamino)aziridines. Generation and Trapping of Monosubstituted Azamines

Article abstract of DOI:10.1021/jo00261a011

The thermolysis of 7-<<<(9-fluorenylmethyl)oxy>carbonyl>amino>- and 7-(benzoylamino)-7-azabenzonorbornadienes (2a and 2 b) in various solvents has been studied.In the absence of an olefinic trapping agent the major products other than naphthalene are the corresponding hydrazides 6a,b.In cyclohexene as solvent, the aziridines 7a,b are formed, suggesting that the azamine 3 is ejected and captured by the olefin.For the olefin cis-4-methyl-2-pentene the reaction occurs with greater than 95percent stereoselectivity in further agreement with a labile azamine intermediate.Thisrepresents the first demonstration that a monosubstituted azamine has independent existence and reacts with olefin faster than it undergoes 1,2-hydrogen shift.Synthesis of the related 7-phthalimido-7-azabenzonorbornadiene (17) was achieved via rearrangement of the corresponding isophthalimide derivative 18, which could be obtained by reaction of phthaloyl chloride with hydrazine 1.Thermolysis of 17 caused fragmentation to naphthalene and phthaloylazamine 13 as shown by trapping of the latter.This reaction represents a new thermal source of transient species 13.For synthetic purposes more practical intermediates for the generation of 3 are the aziridines 21 and 22.The cis analogues (23) of 21 proved to be relatively stable thermally.A new route is presented for the synthesis of 1-amino-cis-2,3-diphenylaziridine.